A basic process for the production of crystalline, semi-crystalline, and amorphous poly(arylene sulfide) polymers from polyhalo-substituted aromatic compounds, wherein the halogen atoms attached to ring carbon atoms react with an alkali metal sulfide in a polar organic compound at an elevated temperature, is generally known in the art. Due to a continually growing attractiveness towards thermoplastic polymeric resins, a great amount of work has been completed which resulted in the disclosure of methods for both batch and continuous operations to produce crystalline, semi-crystalline, and amorphous poly(arylene sulfide)s from polyhaloaromatic compounds having at least two halogen substituents per molecule. Certain processes for producing crystalline, semi-crystalline and amorphous poly(arylene sulfide) resins result in a liquid reaction mixture comprising a liquid-phase polymer and a polar organic compound which can also function as a solvent for the polymer. Certain other processes for producing poly(arylene sulfide) resins result in a slurry reaction mixture comprising a solid-phase polymeric resin dispersed in a polar organic compound. In order for the polymers produced in these processes to be useful in commercial applications, the polymers must first be recovered from the reaction mixture.
One method of recovering the crystalline and semi-crystalline poly(arylene sulfide) resins from the reaction mixture is by a process referred to as the "flash recovery method". In this process the polar organic compound which can also function as a solvent for the polymer and non-polymeric components of the reaction mixture are vaporized, leaving behind the polymer and non-volatile components. The polymer recovered by this process is generally in the form of a powdery resin. This powdery resin has, among other things, (1) proven to be difficult to filter, (2) resulted in a product that when dried is excessively dusty, (3) necessitated pelletizing the powder for extrusion purposes, and (4) resulted in other problems commonly associated with products of relatively low bulk density.
Increasing the particle size of the powder-like particulate crystalline and semi-crystalline poly(arylene sulfide) resin recovered by the flash recovery method would alleviate most of the aforementioned problems. Therefore, one object of this invention is to provide a method for recovering particulate crystalline and semi-crystalline poly(arylene sulfide) resins from a reaction mixture comprising a liquid-phase poly(arylene sulfide) and a polar organic compound which can also function as a solvent for the polymer, wherein the particle size distribution of the recovered resins result in improved filterability and reduced dustiness as compared to resins recovered by flash recovery methods.
Another object of this invention is to provide a method for recovering particulate crystalline and semi-crystalline poly(arylene sulfide) resins from a reaction slurry comprising a solid-phase poly(arylene sulfide) dispersed in a polar organic compound, wherein the bulk density of the recovered resins is increased as compared to resins recovered by flash recovery methods.
Another process used for the recovery of crystalline, semi-crystalline, and amorphous poly(arylene sulfide) resins from a reaction mixture is the addition of a liquid functioning as a phase separation agent. This liquid should be soluble in the reaction mixture and a nonsolvent of the polymeric resin. When a phase separation agent in the form of a liquid is used to recover the polymer from the reaction mixture, the process results in the recovery of a polymer in the form of relatively large, coarse particles. It should be noted, however, that some of these resin particles agglomerate into large chunks and/or adhere onto the internal walls of the polymerization reactor. Therefore, it is another object of this invention to provide a method for recovering particulate crystalline, semi-crystalline, and amorphous poly(arylene sulfide) resins from a reaction mixture or liquid mixture comprising a liquid-phase poly(arylene sulfide) and a polar organic compound which can also function as a solvent for the polymer, and optionally water, wherein the resulting polymeric particles are uniform in size and do not tend to adhere to each other or to the internal parts of the reaction vessel.
It is yet another object of this invention to provide a method for recovering particulate crystalline, semi-crystalline, and amorphous poly(arylene sulfide) resins from a reaction slurry comprising a solid-phase poly(arylene sulfide) resin dispersed in a polar organic compound or a slurry prepared by slurrying an already formed resin in a polar organic compound, wherein the resulting polymeric particles are uniform in size and do not tend to adhere to each other or to the internal parts of the reaction vessel.